1. Field of the Invention
The present invention relates generally to the field of merchandise theft deterrent systems. More specifically, it relates to a deactivator for deactivating markers on products of various sizes, particularly compact disk and cassette cases.
2. Background of the Art
Pilferage of merchandise is a common and well known problem in retailing environments. In order to reduce the losses caused by pilferage, various article surveillance systems have been devised in order to apprehend or discourage pilferers from removing merchandise from the premises. In typical article surveillance systems, markers are secured to goods. These markers are designed to interact with an electromagnetic or magnetic field placed at the exit of the premises. When the marker passes through the field or "interrogation zone," an alarm is generated. Some markers of this type can be removed from the merchandise at the point of sale, before leaving the premises. Other markers are affixed to the merchandise and remain on the merchandise after it has been purchased and removed from the premises. Such markers are usually deactivated at the point of sale, prior to the merchandise leaving the premises.
One type of deactivatable marker is in the form of an electronic circuit comprising inductance and capacitance elements which resonate at radio frequencies. Another type of marker--a magnetic marker--comprises a strip of soft magnetic material which interacts with a ferromagnetic element made of a hard magnetic material which can be magnetized or demagnetized. The soft magnetic strip resonates and generates harmonics in the presence of a magnetic field having a certain frequency. This allows the marker to be detected. The hard ferromagnetic element can be magnetized or demagnetized, thereby deactivating or activating the marker.
Yet another type of marker is the acousto-magnetic or magneto-mechanical marker. This type of marker comprises a strip of magnetostrictive material and a strip of magnetic material of high coercivity. The magnetostrictive material resonates mechanically in the presence of a magnetic field of a particular frequency. This resonance can be detected by a receiver sensitive to the magnetic field created by the mechanically resonating magnetostrictive material. The marker is ordinarily deactivated by modifying the magnetic bias of the strip of magnetic material.
It is an object of the present invention to provide a deactivator for use at a retail point of sale in order to deactivate a theft-deterrent marker attached to an item of merchandise. More specifically, the present invention provides a deactivator for deactivating magnetic markers or magneto-mechanical markers on objects of various sizes.
While the present invention is not necessarily restricted to the deactivation of magnetic markers, it does address specific issues presented by magnetic and magneto-mechanical marker deactivators of the prior art. Such a deactivator of the prior art may be in the form of a flat pad. In order to deactivate a marker, the merchandise to which the marker is attached is placed on the flat magnetic pad. Because access to the pad is unrestricted, it is possible for items to be placed on the pad inadvertently or in any orientation. It is therefore a further object of the present invention to provide a magnetic deactivator which provides control over the type of object which is subject to the deactivating magnetic field and the orientation of the object in the magnetic field.